The present invention relates to medical stapling devices for applying metal staples to suture living tissue such a disunited skin or fascia.
The prior art is replete with medical stapling devices for use in suturing living tissues. U.S. Pat. Nos. 3,643,851; 3,662,939; 3,837,555; 3,873,016; and 4,014,492 are illustrative of such devices which include means which may be operated to move a plurality of open staples along a track and sequentially into engagement with an anvil so that the staple engaging the anvil will be closed to engage it with tissues adjacent the anvil.
Typically, such stapling devices are rather complex and apply a staple which is rectangular or square in shape after application. Such staples may be applied in different ways.
One way involves manually pulling together and everting (tenting) the edges of tissue (e.g. skin or fascia) to be joined, placing the anvil of the stapling device transverse of the juncture between the tissues, and activating the device to apply a staple. The applied staple has a straight central portion (which contacted the anvil) extending across the juncture of the tissues, straight side portions of the staple on either end of its central portion extending along the outer surfaces of the tissue and at right angles to the central portion of the staple, and generally aligned pointed end portions piercing the tissue and extending toward each other from the ends of the straight portions opposite the central portion.
Another way involves bringing the anvil and separated sharp end portions of an open staple into contact with the surfaces of tissues to be joined while the surfaces of the tissue are co-planar, and then activating the device so that the end portions of the staple enter the tissues and pull them together as the staple is closed.
Subsequent to at least partial healing of the tissues, these staples are removed by using a tool to bend the central portion of each staple to a U-shaped configuration, which bending causes the pointed end portions of the staple to separate.
Such stapling of living tissues has presented certain problems. First the open staples are pre-bent at right angles between their side and end portions. When the staple is used to join tissues with co-planar surfaces in the manner described above, these sharply bent portions of the staple must enter the tissue, which can cause tearing of the tissue adjacent the points of entry. Also, either manner of stapling with such staples results in excessive gathering of the tissues to be joined which is not recommended by some experts in the healing art (e.g. by "gathering" we mean pressing together adjacent portions of the tissues to be joined, and by "excessive gathering" we mean pressing together more of those adjacent tissue portions than is required to keep those tissues in contact adjacent and between the staples when a moderate tension is applied across the suture).
After the staples are applied, the healing tissues swell around the staples and enclose significant portions of the side portions of the staples. When the staples are then removed by bending their central portions, their L-shaped side and end portions tend to painfully tear or stretch the joined tissues as they are withdrawn.
Also, tension across the juncture between the tissues can cause some of the applied staples to rotate until the tissues are retained between their opposite corners. Swelling of the tissues around such a rotated staple can obfuscate its orientation so that a person removing the staple may inadvertently bend one of its side portions (instead of its central portion) to a generally U-shaped configuration. This can cause its opposite side and end portion to significantly tear tissues and cause pain as the staple is removed.